1. Field of the Invention
The present invention relates to an optical disk apparatus, a method of recording on an optical disk, and an optical disk, and may be applied, for example, to a minidisk (MD), a compact disk (CD), a digital video disk (DVD), etc., and recording and playback apparatuses therefor. More specifically, according to the present invention, after information regarding copyright is recorded, the level of recording of the information regarding copyright is deteriorated, for example, by an overlapped recording, so that the benefits of the copyright holder are protected more effectively compared with before.
2. Description of the Related Art
Minidisk apparatuses, which are a type of optical disk apparatuses, have been rapidly spreading in recent years because they readily allow copying of various contents of music while not degrading the quality of sound. More specifically, the minidisk apparatuses allow music information distributed via the Internet to be recorded on minidisks for audition, and also allow music on a compact disk borrowed from a friend, etc. to be recorded on a minidisk for audition. Furthermore, music can also be copied from minidisk to minidisk.
Although the easy copying of music, with the sound quality maintained, provides considerable advantages to the user, the benefits of the copyright holder who has created the music may be impoverished. Thus, in organizations and forums such as RIAA (Recording Industry Association of America), SDMI (Secure Digital Music Initiative), CPTWG (Copy Protection Technical Working Group), various approaches have been considered aiming at protection of the benefits of the copyright holder.
As one of the approaches, a method has been proposed in which music information is recorded while being encrypted using copyright protection information which is unique to each storage medium. According to this method, if the music information is copied to another storage medium, decryption is inhibited because the copyright protection information differs from storage medium to storage medium. Accordingly, unrestricted copying of the music information is prevented, thereby protecting the benefits of the copyright holder.
As methods of recording the copyright protection information, for example, a method in which a sector inhibited from user access is provided and the copyright protection information is recorded in the sector, and a method in which a reflection film is partially removed from recording of primary data in the form of a pit sequence so that the copyright protection information is recorded in the form of bar codes (International Publication No. WO97/14144), have been proposed.
These methods, however, are not still practically sufficient to effectively protect the benefits of the copyright holder.
More specifically, in accordance with the method in which the copyright protection information is recorded in the sector inhibited from user access, while the copyright protection information can be recorded relatively easily, the copyright protection information is rather susceptible to copying.
In accordance with the method in which the copyright protection information is recorded in the form of bar codes by partially removing the reflection film, recording of the copyright protection information can be visually checked by observations using a microscope, etc., for the purpose of copying. Thus, so-called pirated editions cannot be fully prevented. Instead of removing the reflection film, in another method, an opaque film may be partially formed on the surface of an optical disk, the copyright protection information being recorded in a similar manner. However, this method also suffers the similar problem as in the method in which the reflection film is partially removed.
The present invention has been made in view of the above, and an object thereof is to provide an optical disk apparatus, a method of recording on an optical disk, and an optical disk which serve to protect the benefits of the copyright holder more effectively compared with before.
To this end, according to a first aspect of the present invention, an optical disk apparatus is provided. The optical disk apparatus includes a recording unit for recording information regarding copyright by irradiating an optical disk with laser beams; and a controlling unit for controlling the recording unit so that, after the information regarding copyright has been recorded in a predetermined area on the optical disk, the level of recording of the information regarding copyright is deteriorated by irradiating the predetermined area with the laser beams.
According to a second aspect of the present invention, a method of recording information regarding copyright by irradiating an optical disk with laser beams is provided. The method includes the steps of recording the information regarding copyright in a predetermined area of the optical disk, and deteriorating the level of recording of the information regarding copyright by irradiating the predetermined area with laser beams.
According to a third aspect of the present invention, an optical disk apparatus which irradiates an optical disk with laser beams so as to play back data recorded on said optical disk is provided. The optical disk apparatus includes a playback signal output unit for outputting, by irradiating the optical disk with the laser beams and detecting light returning therefrom, a playback signal whose signal level changes according to mark sequences formed on the optical disk; a pattern determination unit for determining a pattern of the mark sequences formed on the optical disk; a decoding unit for eliminating variations of the signal level of the playback signal due to the mark sequences based on a determination result of the pattern determination unit and determining the signal level, and for playing back information regarding copyright recorded on the optical disk; and a controlling unit for controlling access to the optical disk using the information regarding copyright.
According to a fourth aspect of the present invention, an optical disk including an information recording surface is provided. In the optical disk, information regarding copyright is recorded in a predetermined area of the information recording surface, and the level of recording of the information regarding copyright is deteriorated by irradiating the predetermined area with laser beams.
According to the first and the second aspects, after the information regarding copyright is recorded in the predetermined area of the optical disk, the predetermined area is irradiated with laser beams, deteriorating the level of recording of the information regarding copyright. Thus, the information regarding copyright is inhibited from playback and detection. Accordingly, the benefits of the copyright holder can be protected more effectively compared with before.
According to the third aspect, the signal level is determined while eliminating the variations of the signal level of the playback signal due to the mark sequences, the information regarding copyright, recorded on the optical disk, is played back, and access to the optical disk is controlled using the information regarding copyright. Thus, even if, after the information regarding copyright is recorded in the predetermined area of the optical disk, the level of recording of the information regarding copyright is deteriorated by irradiating the predetermined area with laser beams, the information regarding copyright, recorded on the optical disk, is allowed to be played back.
According to the fourth aspect, after the information regarding copyright is recorded in the predetermined area of the optical disk by irradiation of laser beams, the level of recording of the information regarding copyright is deteriorated by irradiating the predetermined area with laser beams. Accordingly, the optical disk serves to protect the benefits of the copyright holder effectively.
In all, according to the present invention, after the information regarding copyright is recorded, the level of recording of the information regarding copyright is deteriorated, for example, by an overlapped recording. Accordingly, the benefits of the copyright holder can be protected more effectively compared with before.